CVE-2026-63830

What it is

In the Linux kernel, the following vulnerability has been resolved: net: skmsg: preserve sg.copy across SG transforms The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-19 12:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-22 18:14 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 9.4 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-07-19 12:16 UTC

Last modified

2026-10-22 18:14 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-863 · Incorrect authorization

Record status

Analyzed

Affected

• Linux Kernel < 5.10.261
• Linux Kernel < 5.15.212
• Linux Kernel < 6.1.177
• Linux Kernel < 6.6.144
• Linux Kernel < 6.12.95
• Linux Kernel < 6.18.38
• Linux Kernel < 7.1.3

Attack profile CVSS 3.1 · 9.4

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

Low

Is it in your code?

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